Captain AJ!
I tried Gibralter once. Had to go there after having my base moved to LaSpezia. Hugged the African coast, at night and as fate would have it drew a medium fog weather situation in the spring of '41. Got through by the hair of my chinny-chin-chin. We encountered a task force, just on the med side of Gibralter. Sank a Queen Elizabeth battleship, and paid for that with 36 hours of intense depth charging. The Tommies were NOT happy with us. Thought we were goners for sure. Around 1 pm the following day, a group of Stukas attacked the escorts, and caused enough distraction we were able to slip away. Whew. Gibralter is not for the faint of heart. The fog and darkness allowed us to travel topside for around 50% of the journey. As tough as it was, I can see how light fog, or no fog, or later in the war when engine noise is detectable topside would make the passage extremely perilous.
-Wayne, U203 Lorient